Re: UDLD / Port-Channel Question

mattipler · ‎10-12-2017

Hey guys!

I have a stacked 3850 (2 switches). This 3850 connects into two stacked 2960's, both 2960 stacks also comprising of 2 switches.

The connection between the 3850 and 2960 1 + 2 is through fibre port-channels containing 2 physical ports linking the 3850 to the 2960s.

2960 1 <-> 3850 (port-channel1)

2960 ports GI1/0/49 + GI2/0/49
3850 ports TE1/1/1 + TE2/1/1

2960 2 <-> 3850 (port-channel2)

2960 ports GI1/0/49 + GI2/0/49
3850 ports TE1/1/2 + TE2/1/2

This creates my port-channels and all is well (see below)!

2960 Switch 1

switch1#show etherchannel port-channel
Channel-group listing:
----------------------

Group: 1
----------
Port-channels in the group:
---------------------------

Port-channel: Po1
------------

Age of the Port-channel = 0d:00h:40m:38s
Logical slot/port = 9/1 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi1/0/49 On 0
0 00 Gi2/0/49 On 0

Time since last port bundled: 0d:00h:00m:31s Gi1/0/49
Time since last port Un-bundled: 0d:00h:34m:06s Gi1/0/49

2960 Switch 2

switch2#show etherchannel port-channel
Channel-group listing:
----------------------

Group: 2
----------
Port-channels in the group:
---------------------------

Port-channel: Po2
------------

Age of the Port-channel = 0d:00h:03m:10s
Logical slot/port = 9/2 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi1/0/49 On 0
0 00 Gi2/0/49 On 0

Time since last port bundled: 0d:00h:02m:53s Gi2/0/49
Time since last port Un-bundled: 0d:00h:03m:10s Gi2/0/49

3850

3850#show etherchannel port-channel
Channel-group listing:
----------------------

Group: 1
----------
Port-channels in the group:
---------------------------

Port-channel: Po1
------------

Age of the Port-channel = 0d:00h:40m:52s
Logical slot/port = 12/1 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Te1/1/1 On 0
0 00 Te2/1/1 On 0

Time since last port bundled: 0d:00h:03m:37s Te1/1/1
Time since last port Un-bundled: 0d:00h:37m:12s Te1/1/1

Group: 2
----------
Port-channels in the group:
---------------------------

Port-channel: Po2
------------

Age of the Port-channel = 0d:00h:23m:53s
Logical slot/port = 12/2 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Te1/1/2 On 0
0 00 Te2/1/2 On 0

Time since last port bundled: 0d:00h:04m:08s Te2/1/2
Time since last port Un-bundled: 0d:00h:04m:25s Te2/1/2

However! I then globally enable UDLD aggressive on the 3850... no problem.

But when I then globally enable UDLD on the 2960s, UDLD puts one of the ports in each of the port-channel in error shutdown...

Switch 1

Oct 12 09:16:54.182: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/0/49, unidirectional link detected
Oct 12 09:16:54.182: %PM-4-ERR_DISABLE: udld error detected on Gi1/0/49, putting Gi1/0/49 in err-disable state
Oct 12 09:16:55.185: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/49, changed state to down
Oct 12 09:16:56.188: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/49, changed state to down

Switch 2

Oct 12 09:16:46.236: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/0/49, unidirectional link detected
Oct 12 09:16:46.236: %PM-4-ERR_DISABLE: udld error detected on Gi1/0/49, putting Gi1/0/49 in err-disable state
Oct 12 09:16:47.243: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/49, changed state to down
Oct 12 09:16:48.246: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/49, changed state to down

The fibre is new and I think both going into shutdown is more likely to be an oversite or lack of understanding on my part rather than physical issue with the fibre.

Any help with this greatly appreciated guys!

Matt

chrihussey · ‎10-12-2017

Hello,

Could you post the configs of the port-channel and member interfaces of the switches?

Thanks

chrihussey · ‎10-12-2017

Sorry, but can you also identify the versions of IOS on all switches? There are plenty of bugs associated with UDLD and port channels.

Julio E. Moisa · ‎10-12-2017

Hi

Also you could disable the UDLD reestablish the ports and execute a show etherchannel summary, then enable UDLD.

Thank you in advance.

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

mattipler · ‎10-12-2017

Thank you guys! Really appreciate the help. Please see below...

Question 1

Hello,

Could you post the configs of the port-channel and member interfaces of the switches?

Thanks

Switch 1 (2960)

Port-channel 1

Switch1#show run int po1
Building configuration...

Current configuration : 225 bytes
!
interface Port-channel1
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
end

Physical Interfaces

Switch1#show run int gi 1/0/49
Building configuration...

Current configuration : 281 bytes
!
interface GigabitEthernet1/0/49
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
end

Switch1#show run int gi 2/0/49
Building configuration...

Current configuration : 281 bytes
!
interface GigabitEthernet2/0/49
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
end

Switch 2 (2960)

Port-channel 2

Switch2#show run int po2
Building configuration...

Current configuration : 225 bytes
!
interface Port-channel2
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
end

Physical Interfaces

switch2#show run int gi 1/0/49
Building configuration...

Current configuration : 281 bytes
!
interface GigabitEthernet1/0/49
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 2 mode on
end
switch2#show run int gi 2/0/49
Building configuration...

Current configuration : 281 bytes
!
interface GigabitEthernet2/0/49
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 2 mode on
end

3850

Port-channel 1

3850#show run int po1
Building configuration...

Current configuration : 275 bytes
!
interface Port-channel1
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
spanning-tree guard root
end

Physical Interfaces

3850#show run int te1/1/1
Building configuration...

Current configuration : 284 bytes
!
interface TenGigabitEthernet1/1/1
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
end

3850#show run int te2/1/1
Building configuration...

Current configuration : 284 bytes
!
interface TenGigabitEthernet2/1/1
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 1 mode on
end

Port-channel 2

3850#show run int po2
Building configuration...

Current configuration : 274 bytes
!
interface Port-channel2
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
spanning-tree guard root
end

Physical Interfaces

3850#show run int te1/1/2
Building configuration...

Current configuration : 283 bytes
!
interface TenGigabitEthernet1/1/2
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 2 mode on
end

3850#show run int te2/1/2
Building configuration...

Current configuration : 283 bytes
!
interface TenGigabitEthernet2/1/2
switchport trunk native vlan 999
switchport trunk allowed vlan 10,15,20,25,30,35,40,45
switchport mode trunk
switchport nonegotiate
channel-group 2 mode on
end

Question 2

Sorry, but can you also identify the versions of IOS on all switches? There are plenty of bugs associated with UDLD and port channels.

Switch 1

Switch1#show ver
Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.2(2)E6, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Fri 16-Dec-16 21:27 by prod_rel_team

ROM: Bootstrap program is C2960X boot loader
BOOTLDR: C2960X Boot Loader (C2960X-HBOOT-M) Version 15.2(3r)E1, RELEASE SOFTWARE (fc1)
Switch1 uptime is 20 hours, 38 minutes
System returned to ROM by power-on
System restarted at 16:16:44 UK-BST Wed Oct 11 2017
System image file is "flash:/c2960x-universalk9-mz.152-2.E6/c2960x-universalk9-mz.152-2.E6.bin"
Last reload reason: power-on

Switch 2

Switch2#show ver
Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.2(2)E6, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Fri 16-Dec-16 21:27 by prod_rel_team

ROM: Bootstrap program is C2960X boot loader
BOOTLDR: C2960X Boot Loader (C2960X-HBOOT-M) Version 15.2(3r)E1, RELEASE SOFTWARE (fc1)

Switch2 uptime is 20 hours, 37 minutes
System returned to ROM by power-on
System restarted at 16:14:34 UK-BST Wed Oct 11 2017
System image file is "flash:/c2960x-universalk9-mz.152-2.E6/c2960x-universalk9-mz.152-2.E6.bin"
Last reload reason: power-on

3850

3850#show ver
Cisco IOS Software [Denali], Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version 16.3.3, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2017 by Cisco Systems, Inc.
Compiled Tue 28-Feb-17 05:13 by mcpre

Cisco IOS-XE software, Copyright (c) 2005-2017 by cisco Systems, Inc.
All rights reserved. Certain components of Cisco IOS-XE software are
licensed under the GNU General Public License ("GPL") Version 2.0. The
software code licensed under GPL Version 2.0 is free software that comes
with ABSOLUTELY NO WARRANTY. You can redistribute and/or modify such
GPL code under the terms of GPL Version 2.0. For more details, see the
documentation or "License Notice" file accompanying the IOS-XE software,
or the applicable URL provided on the flyer accompanying the IOS-XE
software.

ROM: IOS-XE ROMMON
BOOTLDR: CAT3K_CAA Boot Loader (CAT3K_CAA-HBOOT-M) Version 3.58, RELEASE SOFTWARE (P)

Question 3

Hi

Also you could disable the UDLD reestablish the ports and execute a show etherchannel summary, then enable UDLD.

Thank you in advance.

Switch 1 port-channel 1 without UDLD

Switch1(config)#do show etherchannel port-channel
Channel-group listing:
----------------------

Group: 1
----------
Port-channels in the group:
---------------------------

Port-channel: Po1
------------

Age of the Port-channel = 0d:03h:31m:04s
Logical slot/port = 9/1 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi1/0/49 On 0
0 00 Gi2/0/49 On 0

Time since last port bundled: 0d:00h:00m:49s Gi1/0/49
Time since last port Un-bundled: 0d:02h:43m:21s Gi1/0/49

Switch 1 port-channel 1 with UDLD

Switch1#show etherchannel port-channel
Channel-group listing:
----------------------

Group: 1
----------
Port-channels in the group:
---------------------------

Port-channel: Po1
------------

Age of the Port-channel = 0d:03h:32m:20s
Logical slot/port = 9/1 Number of ports = 1
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled

Ports in the Port-channel:

Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi2/0/49 On 0

Time since last port bundled: 0d:00h:02m:06s Gi1/0/49
Time since last port Un-bundled: 0d:00h:00m:20s Gi1/0/49

chrihussey · ‎10-12-2017

Hello,

It may be a bug:

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCur31055

Suggest opening a case with Cisco to confirm.

I also experienced the following bug, not exactly the same issue, but:

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb88066

You could try disabling UDLD on one of the affected interfaces and then enabling it again just to see if that is a work around.

Hope this is of some help.

mattipler · ‎10-20-2017

Sincere apologies for not responding to this sooner.

Enabling and then re-enabling did not work.

I'll be recommending that a case is opened with Cisco.

Thank you to everyone that has assisted with this.

Clem58 · ‎05-04-2018

Hello,

We have the same configuration, with the same problem.

Did you resolve this issue ?

Thanks,

Clémence

Clem58 · ‎05-31-2018

I've put UDLD in normal mode on each fiber ports, now the links are not in err-disabled anymore and running well.

So I think it's an issue with UDLD incompatibility in aggressive mode between 2960 and 3850 cisco switches, maybe an IOS update will correct this bug ?